POJ 3988 Selecting Courses (Greedy)

{POJ} {3988} {Selecting courses}

Greedy Algorithm, time is fixed and just find the earlest finished courses.

#include <iostream>

#include <string>

#include <cmath>

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <ctime>

#include <queue>

#include <stack>

#include <list>

#include <algorithm>

using namespace std;

#define rep(a,x,y) for(a=x;a<y;++a)

#define CLR(x,y) memset(x,y,sizeof(x))

int n,ans;

typedef struct{

    int a,b;

}Node;

bool operator<(const Node& a, const Node& b)

{

    if(a.b == b.b)

        return a.a < b.a;

    return a.b < b.b;

}

int work()

{

    int i,j,tmp;

    int a,b,k;

    bool v[500];

    Node node[500];

    while(scanf("%d",&n)) {

        if( 0 == n )

            break;

        rep(i,0,n)

            scanf("%d%d",&node[i].a,&node[i].b);

        sort(node,node+n);

        ans = 0;

        rep(i,0,5){

            rec = 0;

            tmp = 0;

            CLR(v,0);

            for( j = i; j < 1005; j += 5){

                rep(k,0,n) {

                    if( !v[k] && node[k].a <= j && node[k].b > j ){

                        v[k] = true;

                        ++tmp;

                        break;

                    }

                }

            }

            if( ans < tmp )

                ans = tmp;

        }

        printf("%d\n",ans);

    }

    return 0;

}

int main()

{

    work();

    return 0;

}